1. Field of the Invention
The present invention relates to a fixing control device, a fixing control method, and an image forming apparatus which are adapted to control a fixing device including a plurality of heaters to fix an image based on image data to a recording material.
2. Description of the Related Art
Conventionally, there is known an image forming apparatus including a fixing device utilizing a laser beam or a thermal head with good thermal response. In a conventional image forming apparatus including a fixing device, only an area (image area) on a recording material where a toner image is formed or the neighborhood of the area, based on digital image data is selectively heated to fix the non-fixed toner to the recording material. See Japanese Laid-Open Patent Publication No. 7-225524.
In the above-described method, the heaters are simply turned ON and OFF based on the presence of an image on the recording material, and the frequency of turning ON and OFF the heaters is increased. Turning ON and OFF the heaters may produce a rapid voltage fluctuation. Hence, if turning ON and OFF the heaters is frequently performed, the output power of a power source, such as a commercial power source, which is supplied to the image forming apparatus, fluctuates and the possibility of occurrence of flicker increases.
In order to prevent the occurrence of flicker, it is known that a preset temperature of a temperature control of a thermal fixing unit is gradually changed to a target temperature at intervals of a predetermined period of time, and the amount of change of the power supplied to the heat source (fixing heater) is restricted. See Japanese Patent No. 3454988.
However, if the occurrence of flicker is prevented using the above-described method, the response of a temperature change to the area to be heated deteriorates, and the possibility of occurrence of poor fixing increases.